Abstract: Current models of brown-dwarf formation and evolution may be correct but do not yet have a strong underpinning of observational support. The most critical missing data are directly measured masses and gravities for sub-stellar objects with different surface temperatures and luminosities. As with main sequence and post main sequence stars, these masses must come from orbital determinations for binaries. The recent discovery by Stassun et al. of 2M0535-05-an eclipsing binary system in the Orion Nebula Cluster comprising two young brown dwarfs-provides the first direct, accurate measurements of the masses, radii, and gravities of young sub-stellar objects. At the same time, with emergence of sensitive high resolution spectrometers on large telescopes, we now have the capability to measure fundamental stellar properties from spectroscopy alone. This technique relies on precise fits of photospheric lines, which are fully resolved in brown-dwarf spectra at high resolution, to synthetic spectral templates. We propose to apply this technique to the eclipsing brown-dwarf binary 2M0535-05 with Keck HIRES, in order to calibrate and apply this technique as a reliable way to anchor young brown dwarfs on the H-R diagram, and to test and inform theoretical models of brown-dwarf evolution. Through a previous NOAO Keck HIRES proposal, we have successfully observed and analyzed the isolated spectrum of the more massive brown dwarf in the system (Mohanty, Stassun, & Doppmann 2010). Here are we are requesting to observe and analyze the isolated spectrum of the less massive brown dwarf in the system in order to complete our comprehensive study.